According to a 2008 IDC white paper, 2007 marked the "crossover" year, when there was more digital data created than data storage to host it. The IDC report also projected that by 2011 the amount of digital data created will be more than twice the amount of available storage.
We accumulate more and more digital documents, photos, music, and video. Higher-resolution cameras and video equipment increase demand for more and more hard drive space. Over time, the risk of data loss and format obsolescence increases.
Here are three things you can do right now:
Make a plan: Determine who is going to be in charge of your digital data once you are no longer capable of looking after it.
Make multiple copies: When it comes to valuable data, store it in different formats at different locations
Migrate to new technologies: Don't wait for storage media to become obsolete, migrate to new technologies and formats as they become available.
I'd go further, encouraging the use of folder organization and some paper and digital READ.ME-type files to delineate the purposes and intended longevity of your files. Make it obvious which files are the masters and which are just backup copies.
Think about which files should survive you and make it easy for your heirs to handle your data.